


Amor Matris

by undertailsoulsex



Category: Undertale (Video Game)
Genre: Alternate Universe - Underfell (Undertale), Blood and Injury, Broken Bones, Choking, F/M, Flirting, Food Poisoning, Force-Feeding, Forced Illness, Gore, Implied/Referenced Dubious Consent, Imprisonment, Non-Consensual Drug Use, Post-Undertale Neutral Route - Empress Undyne Ending, Protectiveness, Sick Character, Underfell Papyrus (Undertale), Underfell Sans (Undertale), Underfell Toriel (Undertale), Yandere
Language: English
Status: Completed
Published: 2021-02-10
Updated: 2021-02-10
Packaged: 2021-03-16 01:13:34
Rating: Mature
Warnings: Graphic Depictions Of Violence
Chapters: 1
Words: 4,022
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/29323764
Author URL: https://archiveofourown.org/users/undertailsoulsex/pseuds/undertailsoulsex
Summary: Worried about the possibility of war, Papyrus urges Sans to take shelter in a safe place -- behind the door in the woods, with the friendly woman who lives behind it. Sans listens to his brother and finds that the woman is more wonderful than he could ever imagine. But he bites off a little more than he can chew.
Relationships: Sans/Toriel (Undertale)
Comments: 2
Kudos: 17





	Amor Matris

**Author's Note:**

> This fanfiction was originally posted in the Lattices & Cracks fanzine, which you can download for free [here](https://lattices-and-cracks.itch.io/fanzine).
> 
> My partner with this project was [Beetle](https://twitter.com/beetleevil) who illustrated the fic beautifully. You can find her illustrations on Twitter here (will update with link).  
> My beta was [Sesu](https://twitter.com/SesuRescue) who is as awesome as always.
> 
> I kinda lost the drive to provide an extended version of this fic but figured there might be some people interested in reading it here. I still recommend downloading the fanzine because it's presented how I want it there, plus you get to see all the other contributors' great work!

“knock, knock.”

“Who is there?”

“pardon.”

“Pardon who?”

“pardon my french but i fucking adore you!”

Silence. Terrible, soul-gripping silence. But then....

“Ha ha ha! Oh, that’s so sweet!”

Sans sighs, relaxing against the door. She’s laughing. She doesn’t hate him.

“I must say, I find you a- _door_ -able too!” she says, knocking against the sturdy wood.

He’s barking out a full-bellied laugh before the pun registers. The cold is no match for the warmth spreading throughout his face.

\---

It’s an unnervingly quiet trip home, which isn’t unusual in this area after the human’s visit. The chirpy conversations between neighbors, the squeals of kids as they rush home from school, the clinking of glasses during happy hour at Grillby’s. All memories of a bygone era.

Despite that, he’s grinning the entire journey. It’s been a while since he’s felt like this. Happy. Genuinely happy.

That feeling diminishes as he enters the house. Papyrus is sitting on the couch, glaring at the television like it’s insulted him.

“it works better if you turn it on, bro,” Sans quips, though his smile slips. “you good?”

Papyrus just continues to sulk. Hardball, huh? Well, Sans knows how to coax it out of him. He wordlessly grabs the old stuffed bunny and heats up a fresh cup of cocoa. By the time Papyrus has both of them in hand, the tears have started to spill.

It’s the usual. The new usual, anyway. Undyne’s pulling some inane shit—stationing Royal Guards where they don’t belong, pulling in old favors. This time, however, she’s dredged up an old rivalry in New Home, and Papyrus is convinced they’re on the brink of war.

“SHE KEEPS SAYING IT’S TIME TO CONSCRIPT.”

“won’t happen, paps,” Sans soothes. “undyne’s just gonna get her ass kicked.”

“SHE’S INSISTENT. SHE SAYS WE NEED NEW LEADERSHIP TO RETURN TO THE SURFACE.”

“and that’s gonna be her?” He shakes his head. “look, i know undyne. how about i go down there tomorrow and –”

“NO,” Papyrus snaps, clinging fiercely to Fluffy Bunny.

“bro, come on.”

“NO!” he repeats. “PROMISE YOU WILL NOT VISIT THE CAPITAL.”

Sans rolls his eyes. “yeah, yeah.”

That's his little bro in a nutshell. Always trying to keep everyone out of trouble. Cute sometimes, but annoying too.

“AND IF YOU GET DRAFTED—”

“i’m not gonna—“

“IF YOU DO! PROMISE ME YOU WILL RUN!” Papyrus sniffles. “YOU’RE... TOO FRAGILE.”

Yeah, he couldn’t take a hit or he’d crumble like a popato chisp, but all he’d need is one blaster and – Well, Paps doesn’t need to know that.

“okay. promise.”

It won’t come to that, but Papyrus is all worked up. Thankfully, Sans’s reassurances have pacified him; he sighs, squeezes Fluffy Bunny, and after a couple minutes of reflective silence, he turns to him, grinning devilishly.

“SO WHAT WERE YOU SO HAPPY ABOUT?”

Sans blinks at the abrupt change of topic. “what do you mean?”

“YOU CANNOT HIDE IT FROM ME! YOU WERE SMILING!” Papyrus pokes Sans in the midriff. “WAS IT YOUR ‘FRIEND’ BEHIND THE DOOR?”

Sans blushes. “heh. nothing gets past you.”

Papyrus claps excitedly and invites further detail. As Sans spills the beans, Paps hangs onto every word, eating up the romantic crap with insatiable hunger.

“YOU TWO ARE SO SWEET! DO YOU THINK I WILL BE AN UNCLE?”

“what? no! that’s not –”

“NYEH HEH! I AM KIDDING, SANS. THOUGH I DO THINK IT IS HIGH TIME I MEET THIS OLD LADY.”

“yeah?”

“YES. I WOULD LIKE TO KNOW HER INTENTIONS.”

“heh. butting in again? classic papyrus.”

Papyrus grumbles but grins as he finishes his cocoa.

\---

The Guards show up one day. Papyrus was right; they’re drafting able bodies and refusal isn’t an option.

“GO TO THE OLD LADY,” Papyrus hisses, urging him through the back window.

“her? but—”

“SHE AND I HAVE ALREADY DISCUSSED IT. NOW GO!”

When had they even met?

“PLEASE!”

He obeys without further question.

The main path is littered with Guards, but the woods are empty. He trips over roots and rocks, but pushes through the bruises and scrapes. As he spots the Ruins door, his soul twists with anxiety, anticipation. Sanctuary lies on the other side, and when he flings open the door, it’s not quite so much like he’s fleeing anymore, but rather stepping into another world.

He isn’t expecting to immediately see her; it’s not like she lives right on the other side of the door. Yet there she stands, wide-eyed and still.

Truth be told, he’d never really had an image of her. In his mind, she’d always been a disembodied voice. A concept more than a real monster. But as they stand there, speechless, there’s one thing that stands out above all else: her beauty. “Old lady” his ass.

“Hello?” Her musical voice warms the dank hall. “Who are you? What do you want?”

Sans sighs, calming his nerves as he approaches. With his trademark smirk (and zapper to boot), he extends his hand.

“the name’s sans.”

She doesn’t accept his hand, but a smile stretches across her face. “It’s you.”

There’s so much affection in her words that Sans can’t help but grin back—this time less a smirk and more a warm welcome.

“I was wondering when you would gather the courage. Come,” she says, motioning down the hall. “You simply must join me for tea.”

\---

Her name is Toriel. Toriel. It’s such a familiar name, but Sans can’t place where he’s heard it before. Maybe from that old legend about the Angel of the Underground. It’s that sort of name. Mythical. Powerful. Toriel.

In any case, Toriel’s company is the best thing he could’ve gotten. Sure, her cooking is old-fashioned, and she really favors bitter flavors, but it’s a million times better than Papyrus’s stuff. Besides, it’s cozy next to her fireplace, and they share rich discussions about the Underground’s biodiversity, the thermodynamic benefits of the Core, and ways to improve monsterkind’s educational system. He hasn’t enjoyed anyone’s companionship like this in ages. And she admits the same too.

“I’m afraid I’m just a lonely old lady, Sans. I don’t do much but read and knit.”

Heh. There’s so much more to her than that. They take long walks, cook mouthwatering meals, and spend the day joking. For someone who doesn’t spend much time with others, she’s very good at friendship.

She can be shy though. Often, she leaves the house to explore the Ruins, impressing upon him the need for solitude, and although she says she’s friendless, she texts someone at least once a day. Plus she’s blockaded half the house. “Bad memories,” she says.

Sans doesn’t mind. In fact, he’s glad she’s independent. It’s a nice change from taking care of Paps.

She’s generous too. She happily offers her couch, and one night, her bed. Yeah, they’re moving fast, fast enough that had she been any other monster he would’ve thought it a fling. But with her? No. It’s more than that.

Waking up beside her, stroking her fur as she sleeps... well, it’s a comfort he hasn’t felt in ages.

\---

Occasionally Sans texts Papyrus, but his replies are frustratingly blunt and admonish him for risking exposure.

Sans expresses his irritations to Toriel, but she quietens him with a kiss.

“He is just worried about you. Though it is for naught.” Something clouds her expression. “No war shall ever touch you.”

“huh?”

“Oh, nothing,” she says radiantly. “Say, have you ever read Peek-A-Boo with Fluffy Bunny? It is one of my favorites!”

\---

“To new beginnings!”

“to new beginnings.”

They clink their glasses together and Sans swallows a deep draught of dandelion wine. It’s sweet with a slight tang, almost like white wine.

“Snails?”

“don’t mind if i do.”

He dishes some roasted snails next to the dandelion salad and spiced berry medley.

“still can’t believe how fast you whipped this up. looks amazing.”

Toriel blushes. God, his soul can’t take her beauty.

“Of course! I don’t want you leaving without celebrating our newfound companionship.”

“companionship, huh?” He winks. “guess you could call it that.”

Her face reddens more. Heh.

The feast is such a sweet gesture, especially when he’ll only be gone long enough to check on Papyrus—his replies have been so short and he’s a little worried—but she insisted and he can’t say no to her. Besides, all the food looks amazing.

Especially the mushroom soup. The rich, earthy smell has him salivating. He fills his bowl to the brim, then slurps it, piping hot, directly from the dish.

“Ahem! _What_ are you doing?”

Sans freezes. Fuck. He should’ve known a high-class lady like her wouldn’t appreciate shitty table manners. There’s no doubting the fury in her eyes. She’s looking at him like a disgusting roach.

“Hee hee! Just kidding!” She covers her fangs as she giggles. “You should see the look on your face!”

Sans is stunned by the whiplash of emotions, but then snorts, dribbling soup down his chin. Now Toriel is laughing even harder, and though he’s soaked in soup, the laughter is infectious.

“guess i’m _souper_ excited to eat.”

“I can tell!” She reaches over and tenderly wipes his face, like Sans does for Paps. “But if you are not careful, you will not have _mushroom_ for dessert. You do not want to miss out on my butterscotch-cinnamon pie.”

“you underestimate my capacity for good food.”

“Oh?” She leans forward with a flirtatious smirk. “I bet you cannot eat it all.”

“heh. what’re you betting?”

“Hmm. If you fail to eat everything, I get to keep you a little longer. And if you win–” Her mouth curls. “Well, I could send you off with a _bang_. If you catch my drift.”

Sans ties a napkin around his neck like a bib. “you’re on.”

To say the food is delicious is the understatement of the century. Although there’s that familiar bitter undertone to everything, Toriel has worked it to her favor. It plays off the sweetness of the flowers and berries, the snails’ richness, the soup’s umami. It’s a culinary masterpiece in which Sans is delighted to partake.

Toriel is clearly impressed with his eating skills. Or horrified. She’s wide-eyed and blushing as she watches. Wine always makes it easier to gorge himself, but he’ll keep that quiet; it’s his secret weapon to battle this smorgasbord.

As he rounds off the soup, though, he wavers. Physically. It’s hard to tell at first, given how the alcohol has hazed his vision, but there’s no mistaking the way his hand keeps fumbling the next plate, like something’s preventing his fingers from flexing. And his back can’t seem to properly hold his weight.

Toriel says something, but he can only blink lazily at her blurred form. He slumps into his chair, arms hanging uselessly at his side.

At some point, Toriel’s soft arms cradle him. With her boss monster soul humming close to his head, he relaxes into a peaceful slumber.

\---

Something’s wrong with him.

He’s buried in a mountain of blankets, trembling with fever. Every time he shifts, he feels as though his bones are weighed down. They’re sluggish. Heavy. When he tries to push past the weight to move, it’s like electric shocks jolt through his limbs, pricking deep into his marrow. Moving his spine is the worst; his cervical vertebrae pinch tight, as if caught in a vice. All he can do is shut his eyes and wait for the moment to pass, and when it finally does, he can’t even lift his arms to wipe away his tears.

It’s lucky he has Toriel to take care of him. She must’ve dragged his pathetic ass from the kitchen to the bedroom, a feat only someone as strong as her is capable of. To his surprise, though, he’s not in Toriel’s room, but another bedroom entirely. Her dead kid’s room? Toriel had mentioned it at some point last night. Sans isn’t sure when, exactly. The half-memory is tainted with nausea and exhaustion.

In any case, it’s creepy as hell. Old crayon drawings plaster the walls, he’s stuck in a kid-sized bed (which fits him perfectly), and several pairs of worn-out children’s shoes are tucked halfway under the bedframe. She’s got it set up like her kid has just ducked out to play with some friends or something. Like they aren’t dead.

He’s exaggerating, he knows. The room isn’t that weird, and it makes sense why a grieving mother would cling to the last memories of her child. It’s just bizarre that she brought him here.

In any case, she knows how to baby him. Every couple hours she comes in to check on him, her worry plain as day. She wipes the sweat from his brow, administers medicine, and at mealtime, props him up with pillows and handfeeds him more of that soul-warming soup. It hurts dreadfully every time she moves him, but her tender touches are worth it.

“There, there,” she coos as she strokes his skull. “You will feel better soon.”

Oh, but he already feels better.

\---

His phone is gone.

He only realizes it after a few days, when Toriel’s been gone several hours, off to forage. His head has cleared, which is odd since he hasn’t eaten since this morning. He tries to sit up, and—

“oh fuck,” he hisses as his bones audibly pop. Shit, that hurts.

It takes a few tries, but he manages to nudge the covers off his body. He freezes as he spots his bare bones. When had she stripped him? And _why_?

He shakes off the distraction. Last he remembers, his phone had been in his pocket. Or was it the kitchen? Or it could’ve been the dining table.

It’s so hard to focus, his thoughts keep straying to other topics like his brother, the feast, the soft kisses....

And his body. He can’t tear his gaze from his ribcage. The bones are slicked with sweat, and the color.... Is it the lighting? Or are they really that dull, dusty grey? Some of his ribs even look semi-transparent, like they’re comprised of misty glass. And he’s never been a stranger to cracks—it’s impossible to avoid, for someone as fragile as him—but there’s hundreds of tiny fissures lacing his spine and arms that weren’t there before.

Panic firmly nestles into his chest. Holy shit. This isn’t right. Fuck, fuck, fuck!

“I have returned!” Toriel calls, her singsong voice carrying through the door. By the time she enters the room, however, Sans’s fear has wrung tears from him.

“Oh my – What is wrong, Sans?” she cries, dropping the basket of mushrooms as she rushes to his side. “Are you in pain? Let me administer your—”

Sans grabs her arm. Attempts to anyway. His fingers can’t close, and even that simple effort leaves him gasping with pain.

“there’s something wrong with me, tori,” he manages. “i’m sick!”

Toriel tuts. “Yes, I know that, buttercup.”

“ _real_ sick! like… i’ve never been this sick.” He’s panting hard enough that it’s hurting his ribs. And is he imagining the cracking noises? “you gotta get me to a healer.”

“I _am_ a healer, Sans.” She draws the blanket over his body, hiding the terrible sight.

“a proper one!”

Toriel stiffens then shakes her head with a sigh. “You would not know this, of course, but I offered medical support during the last war. I know my way around illness and injury.”

“i’m sure you’re great, but please.... i think i’ve got a disease or something. if you could carry me—”

“To where? The hospital? That is all the way in New Home.” She crosses her arms. “There is a war.”

“then call someone. my phone... i can call for a healer. i know some monsters.”

“We do not need to,” she snaps.

“god, listen. i know my own body. this isn’t good. please, check my pocket for my phone.”

“It is not in your pocket.”

She reaches atop the dresser adjacent to the bed. God, it seems so much shorter next to her.

“It’s here,” she says, showing him.

He reaches for it, but his damned arms. Fuck....

“Oh, you wretched thing.” She returns the phone to the dresser and bends down to pet him. “What you need is rest.”

“no,” Sans says very clearly. “what i need is to call someone. a healer. my brother.”

“Your brother,” she says, withdrawing with a sudden and pugnacious fury, “is fine. There is no need to concern him.”

“i don’t care if _he’s_ fine! i’m the one dying here!”

“YOU ARE NOT DYING!” Toriel screams, her eyes maddeningly wide.

It feels like the floor has dropped out from under him. “i–”

“ENOUGH!” Her hands are crackling with flames. She’s bent into a fighting position, body quivering as she stares him down. “NO ONE IS GOING TO DIE!”

Sans might be a fucking idiot (as evident from his current predicament), but he knows when to shut up. He cowers in bed, wincing from pain as he trembles. Eventually the flames sputter away, casting them in the familiar dark, cozy atmosphere. She leaves the room, blank-eyed, sullen, and speechless.

He isn’t sure what to think until she returns later to lay her weight upon him, his bones screaming, popping, snapping, as she force-feeds him more of that God-awful soup. The bitterness fills his palette, and he chokes hard before passing out.

\---

The phone’s on the dresser. Right on the edge. Taunting him. All it would take is a good, solid push.

He’s been staring at it for a week, praying it’ll come down on its own. It’s got to be done. He has to make himself.

That morning he pulls the blankets to his chin. It takes more than a dozen attempts, and it’s barely in time for Toriel’s morning greeting, but he manages.

She fusses over him, wiping away his tears. When she feeds him, she doesn’t notice that when he swallows the soup it spills through his ribcage, soaking the bed. Nor does she notice how he fakes his snores after breakfast. She brushes his skull and assures him she’ll return from her foraging trip soon.

The moment the front door closes, Sans’s eyes open.

The lingering effects of last night’s dosage of drugs have to fade before he begins, otherwise the pain will be paralyzing. But he can’t take too long. She’ll return soon.

Fifteen minutes. That’s how long he allows himself to rest. Any more than that and he risks losing the nerve to do it at all.

He counts the seconds before drawing the blanket off him. It’s much easier than pulling it up; he’s worked out a system of pinching and tugging that doesn’t strain his bones. Once free, he warily eyes the phone atop its pedestal.

It’s time.

With an even breath, he turns towards the towering dresser, hissing through clenched teeth as his spine reverberates with sickening pops. Fuck, FUCK! He’s only moved a couple inches and he’s already panting. Not incapacitated though. He’s got to count every blessing.

Several attempts later and he’s on his side, eyes burning with tears from straining to keep his ribcage and arms leveraged upwards. He swears he can hear his pelvis splintering as it holds his weight. There’s no time to pause, not with the electric pain shooting up his spine, threatening to render him unconscious, so he takes in a shuddering breath and lifts his left arm.

A scream, soft and unbidden, squeezes from between his teeth. His breathing comes rough, scraping his scapula against his ribcage. And his arm.... The pain is blinding as he stretches, stretches, stretches—

CRACK!

His hand lands on the dresser as his ilium gives way. Instant, searing pain bursts through him as his ribcage and right arm crash onto the bed. He flinches, and, unbalanced, his hand skates across the dresser. There’s a voice somewhere, distant, shrieking as he tumbles to the floor. With his arm extended, it takes the impact, though it can’t endure his weight. He can’t see it—everything is too blurry—but he can _feel_ it. The ulna is too weak. SNAP.

He blacks out as his face slams into the floor.

\---

Pain. That’s all he knows, for a time. His body pulses with it, controls him, grips so fiercely that he dare not move.

Sobbing. Hard breathing. Those are the sounds he wakes to. It takes him several minutes to register how the noise correlates with his mouth’s movement. With every inhale, his jaw throbs with renewed pain.

He cracks open his eyes. His mandible.... It’s sitting in front of his face, twisted and half detached. Seeping out the latticed, spongy bone is blood, oddly congealed and brown.

His vision flickers.

Fuck. This is how he dies. Like an idiot.

As he feels the thickened blood pool around his jawbone, he sees his phone. It’s resting near his outstretched, mangled arm, on the floor.

He’s crying again. Maybe laughing. Probably both.

That stops when he hears the front door.

_No_.

Although it takes every inch of willpower, he forces himself not to scream as he extends the last inch and shifts his phone toward him. Fuck. Nowhere to hide it. The bed?

Trembling so hard his bones audibly rattle, he maneuvers his right arm from beneath him. It’s broken too, though instead of a clean snap, the humerus is split like a faultline into three delicate fragments. One wrong move and they’ll splinter. He has to risk it. Pushing through the pain, he wrenches his arm behind him and blindly tucks the phone between the mattress and bedframe.

Are chunks of bone sloughing off him? Has he lost his mind from the pain? Maybe his limbs are detaching. It hurts so badly that he almost wishes it. He giggles mindlessly at the image of an armless skeleton.

By the time Toriel discovers him, he’s unconscious, though a demented smile alights his face.

\---

When he awakens, his arms are a mess of bloodied gauze that barely hide the jagged ends. Toriel can’t heal the left ulna; it’ll remain maimed forever. His right arm—Toriel unwinds the bandages, and between the sight and stench of infection, he nearly vomits.

Yet somehow it hurts less than the rest of his body.

“Do not speak,” she orders, voice gruff, as she tends to his reattached mandible. “Your jaw must heal. Your ribs and pelvis too.”

Sans whimpers, and Toriel’s face darkens.

“If you cannot behave, I will tie you down.” She softens. “Please rest. I care for you too much.”

He wishes she didn’t care about him at all.

\---

Toriel’s deemed it safe to lower his dosage—enough to restrain his magical attacks but not to render him half-senseless from bone pain like before. Regardless, it still hurts too much to move. His attempts end with him crying out for Toriel’s medication and attention.

Attention. He hates it but craves it. He craves _her_. Now that he’s not drugged into a stupor, he’s bored to the brink of madness, and Toriel has punished him by forbidding books. She’s his only source of... comfort.

That’s about to change. Weeks later, he’s finally strong enough to fish the phone from the untouched hiding spot. Thank God, it’s been off this whole time; there’s enough power for one quick call.

“c’mon... c’mon... paps!” Sans whispers as the ringing stops. “you there?”

“SANS?”

“thank fuck. bro, listen to me. toriel—the old lady—has me locked up.”

“YOU—”

“no, wait, my phone’s gonna die. bring as many monsters as you can and get ready to fight—”

“BUT HOW DID—”

“ _papyrus_ ,” Sans hissed, “listen!”

“BUT SHE SAID SHE WAS TAKING YOUR PHONE!”

“stop interrupting, it’s – wait, what?”

His phone...?

“I AM SORRY, I SHOULD NOT HAVE LIED,” Papyrus confesses, “BUT YOU WOULDN’T LISTEN!”

Sans’s mouth dries. “what’re you saying?”

“SHE PROMISED SHE’D KEEP YOU SAFE! UNTIL THE WAR ENDS!”

“you... did this?”

There’s noise in the background. Metal clanging. Magical attacks.

“I MUST GO! WHEN EVERYTHING HAS SETTLED, WE’LL TALK. I LOVE YOU!”

The phone clicks and as he lifts his gaze from the phone, he sees the silhouette in the doorway.


End file.
